The Health Risks Posed by Diesel Bus Emissions

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Originally appears in the Spring 2019 issue.

DIESEL BUSES HAVE BEEN delivering our kids to school for decades, but when it comes to the health risks posed by diesel emissions, our children deserve better.

Diesel emissions, in fact, pose health risks to all of us — students, teachers, parents, bus drivers, and our schools’ neighbors. According to Health Canada, exposure to diesel emissions can increase the risk of lung cancer, cardiovascular disease, worsening of asthma and allergy symptoms, and other health problems (Health Canada, 2016). Children and those from other vulnerable populations, such as asthmatics, seniors, and people with heart conditions and compromised immune function, are at greater risk of harm. There is evidence of possible links between diesel emissions exposure and certain reproductive and developmental effects, and growing concern among scientists about the ability of ultra-fine diesel exhaust particles to reach and potentially harm the developing brain.

Based on a health impact analysis conducted by Health Canada (2016), on-road diesel emissions in 2015 were linked to 320 premature deaths. Diesel emissions are also associated with significant numbers of acute respiratory symptom days, restricted activity days, asthma symptom days, hospital admissions, emergency room visits, child acute bronchitis episodes, and adult chronic bronchitis cases across Canada (Health Canada, 2016).

Exposure
How are school children exposed to diesel emissions? Children may be breathing in diesel emissions while riding school buses, despite regulatory and technological improvements that have drastically reduced the self-polluting potential of newer bus models (Clean Air Partnership & OPHA, 2010). It is estimated that children who are bussed to school spend up to 2,000 hours onboard a school bus between grades K–12 (Équiterre, 2018), so these on-board exposures can add up. Children, parents, and school staff standing beside idling diesel buses waiting to load or unload are also exposed to elevated levels of diesel emissions. Even people in a nearby playground or sports field may be breathing in harmful levels of pollutants. As well, diesel emissions and particulate matter in outdoor air can infiltrate and contaminate the indoor air of the school.

Solutions
So, what can be done, how quickly, and by whom? This year for Healthy Schools Day in Canada, we are shining a spotlight on diesel bus emissions because it is a common and important source of health risk for children. It is also a problem with existing solutions. These include well-recognized solutions such as cleaner transportation technologies and the adoption and enforcement of no-idling policies. There are also some lesser-known measures that can be done now, with relatively little cost, to reduce exposures and help protect health.

When it comes to diesel technologies, progress is being made. Regulatory standards for diesel engines and fuels are more stringent than in previous decades, and retrofitted and newer technology diesel engines are commonplace. All of these efforts are helping to reduce human exposure to diesel exhaust.

Some schools and districts are going the distance by making a clean break from diesel and embracing low- and zero-emission engine technologies such as electric buses. Investing in these cleaner transportation options not only reduces emissions exposure for children and staff; it can help reduce the carbon footprint of our schools. Young people deserve to have climate action modeled in their places of learning: Switching to electric buses, particularly in jurisdictions where electricity is generated by renewable energy sources, can be part of that shift. Indeed, as we’ve seen recently with the student activism inspired by Nobel Peace Prize nominee Greta Thunberg, a growing number of young people are demanding that the adults of the world protect the viability of the planet and our collective future by taking decisive action on climate change.

Concerted efforts by health and environmental organizations, parents and communities have focused attention on the localized and avoidable pollution caused by idling vehicles. The result has been an upsurge in idling by-laws and policies, yet, idling buses remain a common sight. Plausible explanations are offered, such as the need to keep vehicles warm and to avoid problems with restarting the engines, particularly when it is cold. The good news is that there are now relatively low-cost heaters that can be installed on board buses to keep the vehicles warm and defrosted so that engines can be switched off while buses wait for their passengers. These require a fraction of the fuel that would be required to keep the bus engine running (OPHA, 2005), and some versions use electricity instead of diesel (US EPA, undated). Particularly for school districts where the financial resources to replace existing older diesel buses remain out of reach, this can be a practical option to reduce children’s exposures in the near term.
The practice of bus caravanning — buses lining up ‘nose to tail’ with little space between them — can increase onboard levels of pollutants. The California Air Resources Board recommends increasing spaces between buses by staggering departure times to reduce children’s exposure to diesel emissions (CARB, 2016).

Bus driver education is another relatively low-cost and near-term action that can help cut back on the level of diesel emissions exposure for children riding on buses. In addition to minimizing idling and caravanning, drivers can reduce the infiltration of diesel emissions into the cabin by simple means such as keeping the door and windows closed when in traffic and especially when near other diesel-powered vehicles, if weather conditions permit. Regular inspections and preventive maintenance of bus fleets, as well as smart driving practices, such as avoiding rapid acceleration and maintaining a steady speed, can reduce emissions of air pollutants and improve fuel efficiency (Natural Resources Canada, 2018).

The location and logistics of bus loading/unloading zones can be another element of a school’s diesel emission exposure reduction game-plan. If the loading zone is located adjacent to a playground, or if students congregate outside in areas close to bus tailpipes, avoidable exposures may be occurring. School administrators may consider reconfiguring or relocating loading zones, altering traffic flow (Are there ways to speed up the process so that buses are in and out more quickly?), and encouraging the use of outdoor spaces by students and waiting parents to keep people as far away as possible from the pollution emitted by school buses and other vehicles.

School board maintenance staff also have a role to play. A recent study led by Health Canada researchers in Ottawa schools demonstrated the potential value of adjusting the timing of the ventilation system so that large air intakes during morning rush hour are minimized (MacNeill et al, 2016). This can reduce the amount of air pollution drawn inside the school, thereby reducing exposure for students and staff throughout the school day. This common-sense and virtually cost-free concept was adopted by the Ottawa-Carleton District School Board (OCDSB) since, according to Clem Laferriere, “there was a benefit to do so and it was an easy fix that didn’t come with a high price tag” (Ontario School Plant Manager, 2015). This strategy can also be applied to a school’s diesel bus emissions exposure reduction strategy by ensuring that high-volume air exchanges do not occur during busy bus loading/unloading times.

All of these actions — idling reduction measures, avoidance of bus caravanning, fuel-saving and exposure-reducing driving practices, reconfiguration of loading zone location and logistics, and adjustment of school ventilation systems to reduce pollution intake — are practical means to reduce children’s diesel emission exposures today. Parallel to such efforts, administrators, school boards, and governments need to attend to the longer-term objectives of fleet upgrades to reduce or eliminate diesel emissions and reduce the carbon footprint of school transportation services.

School boards typically carry responsibility for optimizing bus routes to minimize travel and, by extension, reduce emissions. In addition to finding the shortest and least fuel-consumptive routes, avoiding routing school buses through areas with high traffic density and/or other pollution sources can also help ensure better on-board air quality.

Another simple way of reducing exposure to all sources of traffic-related air pollution associated with school travel (both diesel buses and gasoline and diesel passenger vehicles) is to promote active school travel: walking or biking to school. There are multiple health benefits from active school travel, including healthier children, less traffic and pollution, safer school zones, and better academic performance (Green Communities Canada, 2018). Programs like the Walking School Bus support schools and communities to set up programs to walk children from home to school and back (Canadian Cancer Society, 2019).

Procurement policies can be another point of leverage for improving the human health and environmental sustainability profile of school bus transportation. Some school boards set requirements around the age of the bus fleet, the use of emission control devices, as well as driver training and idling reduction requirements (Clean Air Partnership & OPHA, 2010). Over the longer term, expect to see greater uptake of electric bus technologies, which, although bearing a higher initial price tag, may have attractive pay-back periods to accompany their public health benefits.

We all want healthy learning environments for our kids. Given what we know about the health risks posed by diesel emissions, we need to use all the tools in the tool box to reduce such exposures for the benefit of students, staff and neighbouring communities. There are decisive actions we can take now, today, on the near-term options that exist, while setting in motion plans for a cleaner, healthier school transportation systems for our children and future generations.

References:
California Air Resources Board (2016). Children’s School Bus Exposure and Mitigation Studies. Online at: https://ww3.arb.ca.gov/research/schoolbus/schoolbus.htm

Canadian Cancer Society (2019). Walking School Bus. http://www.cancer.ca/en/prevention-and-screening/reduce-cancer-risk/get-involved-on/walking-school-bus/?region=on

Clean Air Partnership & Ontario Public Health Association (OPHA). (2010). School Buses, Air Pollution and Children’s Health: Follow-up Report. https://opha.on.ca/OPHA/media/Resources/Resource%20Documents/SchoolBus-FollowupReport-1Oct2010_1.pdf?ext=.pdf

Équiterre (2018). Action of the Month: Encourage School Bus Electrification! Online at: https://equiterre.org/en/news/action-of-the-month-encourage-school-bus-electrification

Green Communities Canada (2018). Making the Case for Active School Travel. http://ontarioactiveschooltravel.ca/wp-content/uploads/2018/04/Making-the-Case-for-Active-School-Travel-Fact-Sheet-and-Reference-List…..pdf

Health Canada (2016). Human Health Risk Assessment for Diesel Exhaust. http://publications.gc.ca/collections/collection_2016/sc-hc/H129-60-2016-eng.pdf
Health Canada, New Brunswick Lung Association, Environment Canada, New Brunswick Department of Education,

Environment and Human Health, Inc. & Research and Productivity Council (2005). Evaluation of the Levels of Diesel-related Pollutants on School Buses During the Transportation of Children – Executive Summary. http://publications.gc.ca/Collection/H128-1-06-455E.pdf

MacNeill, M., et al. (2016). Can changing the timing of outdoor air intake reduce indoor concentrations of traffic‐related pollutants in schools? Indoor Air, 26: 687-701. doi:10.1111/ina.12252. https://onlinelibrary.wiley.com/doi/full/10.1111/ina.12252

Ontario Public Health Association (OPHA) (2005). School Buses, Air Pollution & Children’s Health: Improving Children’s Health & Local Air Quality by Reducing School Bus Emissions. https://opha.on.ca/getattachment/25c418d3-89c9-464f-9c89-e22b5f804103/School-Buses,-Air-Pollution-Children-s-Health.pdf.aspx?ext=.pdf

Natural Resources Canada (2018). Fuel-efficient driving. https://www.nrcan.gc.ca/energy/efficiency/transportation/21042

US Environmental Protection Agency (US EPA) (undated). Clean School Bus Idle Reduction. Online at: https://www.epa.gov/cleandiesel/clean-school-bus-idle-reduction#Tech Accessed April 1, 2019.

Erica Phipps is the Executive Director of the Canadian Partnership for Children’s Health and Environment (CPCHE).

With contributions from: Helen Doyle serves as the Environmental Health Work Group Chair for the Ontario Public Health Association (OPHA). Barb MacKinnon is the President and CEO of the New Brunswick Lung Association.

We would also like to thank Don Huff, President of ECO Strategy, for his assistance in bringing this piece to publication.